LAUNCHER.apk modification help?

I modified my launcher.apk but I can't figure out how to put the modified version on my phone. I would put the file where it belongs /system/app but it fails to install. So I then tried to use ddms to push the file but still the same thing. So I put my phone in recovery to push the through ddms that way, figured maybe phone shouldn't be running, but I can't do anything on ddms when my phone is in recovery.

OK I got it onto my phone but it won't let me erase these 2 files: "ic_tray_collapse.png" and "ic_tray_expand.png". They have a litlle white arrow which I don't want, and if I delete the 2 files the launcher always FCs, so they have to be there but how do I remove the pic of the arrow?

Ok ya thankyou that would be great I tried to make them transparent (atleast I think haha). One though won't let me do it how I did the others. I will just send you the originals so you can do it right lol.